What does it mean and how can I "close" it so I can scan my plugs again??

Sounds like a bug in the VSTi, one you might have to take up with Synthology. Do you mean the UI is invoked during the scan? That's kind of like having the patient wake up during an operation. Ain't supposed to happen.

Hooooo...that's scary!! But yup...I guess that's what's happening. The error dialog just says Ivory open...and hangs the scan. Then there is a dialog that's open BEHIND the scan dialog and X3 that gives you a choice to disable or enable "risky" the plugin. Only thing is to get to that dialog you have to close out the scan. So basically your screwed. I've got travel plans tomorrow but I'll get it all sorted next week. Sheesh!!!!

Try moving the Ivory vst dll file to another location perhaps your desktop. Then run the scan again in sonar. This will get the rest of your things going.
 
Then you could try extracting another copy of the Ivory dll with the installer to see if the file became damaged.

Thanks. I'll give that a whirl. Since Ivory is iLok I'll also try uninstalling and reinstalling.

Found out about this while trying to trouble shoot an EZDrummer2 problem.

Dern it.